What must be done prior to closing the aircraft bin door?

Prior to closing the aircraft bin door, it is essential to ensure that there is a 2-inch bin gap and that the bin netting is properly closed. This process is crucial because it helps secure the cargo and prevents any items from shifting during flight. The 2-inch bin gap allows for proper pressure equalization, which is necessary for the integrity of the bin closure system. Closing the netting ensures that the items are safely contained within the bin and that they do not interfere with the operation of the door or pose any hazards during flight.

Addressing the other options helps place the importance of this procedure in context. Checking emergency exits and inspecting external weather conditions are important safety measures, but they occur separately in pre-flight protocols. Verifying payload weight is also necessary for ensuring balance and safety, yet it does not directly relate to the immediate action of closing the bin door, which focuses on the physical security of the cargo itself.